There are various applications where it is wished to detect and/or monitor ionising radiation. For instance in the nuclear power industry it may be wished to monitor radiation levels at various locations within a power station. In many instances it is desirable that such monitoring can be done remotely and automatically. Likewise hospital radiology departments and other organisations that use radioactive sources may also have a need for installed radiation detectors.
Radiation detectors that are employed to provide monitoring in a given location typically tend to be gaseous ionisation detectors or solid state detectors such as semiconductor radiation detectors.
Gaseous ionisation detectors, such as the well known Geiger-Müller tube, typically comprise two closely spaced electrodes in a gaseous atmosphere with a potential difference applied to the electrodes which is below the breakdown voltage of the gas. In the presence of ionising radiation some of the atoms or molecules of the gas will be ionised and the resulting electrons and ions will allow a current to flow between the electrodes. The flow of a current can be detected and used as an indication of the presence of ionising radiation. The strength of the applied potential difference may be relatively high so as to lead to avalanche multiplication in the gas leading to a relatively large current pulse for each detection event.
Semiconductor radiation detectors operate by measuring the resulting current caused by ionising radiation creating electron-holes pairs in the detector material. Semiconductor detectors can provide fast response times but tend to be more expensive than gaseous ionisation detectors and may require cooling to reduce leakage current.
Such radiation detectors operate at a given location to measure ionising radiation at that location. In many applications multiple different detectors must be located at various locations to provide sufficient coverage, e.g. to provide sufficient areal coverage and/or provide monitoring at different locations within a facility. Each detector must be powered and typically must be able to communicate its readings to a remote location such as one or more control centres. There can therefore be relatively significant cost and complexity in installing such radiation detectors.
Embodiments of the present invention provide radiation detectors that mitigate at least some of these issues.